Receivers for Processing Vestigial Sideband Signals and Processing Methods Thereof

ABSTRACT

Provided is a receiver for processing VSB signal. The receiver includes a first equalizer/decoder unit and a second equalizer/decoder unit. The first equalizer/decoder unit performs a first equalizing operation, first TCM decoding and first RS decoding on a received symbol to output a first dibit. The second equalizer/decoder unit performs a second equalizing operation, second TCM decoding and second RS decoding on the received symbol to output a transport stream. The first dibit is provided as a priori information for a soft-decision operation of the second TCM decoding.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application claims priority under 35U.S.C. §119 of Korean Patent Application No. 10-2010-0031069, filed onApr. 5, 2010, the entire contents of which are hereby incorporated byreference as if set forth fully herein.

BACKGROUND

The present disclosure relates to a digital broadcasting system, andmore particularly, to a receiver for processing vestigial sideband (VSB)signal and a processing method thereof.

Recently, broadcasting systems have been rapidly changing from analogschemes to one or more digital schemes. It is expected that digitalbroadcasting systems may completely replace the existing analogbroadcasting systems after a few years.

Limitations in the theory and actual functionality of digitalbroadcasting systems and/or digital communication systems includeInter-Symbol Interference (ISI) in channels. Various channelequalization techniques have been developed for removing ISI. Suchchannel equalization techniques include, for example, Maximum-LikelihoodSequence Estimation (MLSE), Linear Equalization (LE) andDecision-Feedback Equalization (DFE).

In digital broadcasting systems, various channel coding and errorcorrection techniques are used for correcting errors that occur due tonoise. Particularly, in a digital television (TV) broadcasting systemusing an ATSC 8-VSB scheme, Reed-Solomon Code (RSC) linked withTrellis-Coded Modulation (TCM) may be used.

As an optimal scheme of decoding TCM data that is transmitted through anISI channel where ISI exists, there is joint MLSE called Super Trellis.However, because of complexity that exponentially increases with respectto the time variable characteristics of channels, joint MLSE isrecognized as not being suitable.

As the second scheme for solving such a limitation, there is a schemethat compensates ISI through a Decision Feedback Equalizer (DFE) anddecodes TCM data with a Viterbi decoder. Such scheme is often used inactual works, but may have severe limitations. For TCM data received,the decision feedback equalizer that operates prior to a TCM decoder,should use an uncoded symbol for performing a feedback operation. Thereliability of an uncoded symbol inputted to the decision feedbackequalizer is relatively very low. Consequently, performance enhancementsof the decision feedback equalizer may be limited.

In techniques of decoding TCM data, as an alternative technique that mayhave a small hardware burden and provide performance equivalent to thatof optimal MLSE, the decision feedback equalizer and the TCM decoder (orViterbi decoder) may be connected in cascade. However, the decisionfeedback equalizer references data provided from the TCM decoder insteadof referencing the decision value of a decision unit (for example, aslicer). That is, the decision feedback equalizer uses a symbol decisionvalue using the optimal survivor path of the TCM decoder. Such a schemeprovides better performance than that of a scheme where the decisionfeedback equalizer and the TCM decoder are separately driven. This isbecause the decision value of the TCM decoder using the optimal survivorpath has much higher reliability than that of a decision value by theslicer.

However, the developments of low-cost ATSC receivers having highperformance are still urgently required for the generalization andpopularization of digital broadcasting.

SUMMARY

The present disclosure provides a digital television (TV) receiver,which can enhance reliability of received data at a multipath and timevariable channel environment.

Embodiments of the inventive concept provide a receiver for processingvestigial sideband (VSB) signal including: a first equalizer/decoderunit performing a first equalizing operation, first Trellis-CodedModulation (TCM) decoding and first Reed-Solomon (RS) decoding on areceived symbol to output a first dibit; and a second equalizer/decoderunit performing a second equalizing operation, second TCM decoding andsecond RS decoding on the received symbol to output a transport stream,wherein the first dibit is provided as a priori information for asoft-decision operation of the second TCM decoding.

In other embodiments of the inventive concept, a method for processingvestigial sideband (VSB) reception signal in a receiver, including adecision feedback equalizer, includes: generating a decision value of areceived symbol; performing Reed-Solomon (RS) decoding on the decisionvalue to correct an error; converting the error-corrected decision valueinto a dibit; and performing Trellis-Coded Modulation (TCM) decoding ofthe decision feedback equalizer on the basis of the dibit.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the inventive concept, and are incorporated in andconstitute a part of this specification. The drawings illustrateexemplary embodiments of the inventive concept and, together with thedescription, serve to explain principles of the inventive concept. Inthe drawings:

FIG. 1 is a block diagram illustrating a structure of a Trellis-CodedModulation (TCM) encoder of a digital broadcasting system according tosome embodiments of the inventive concept;

FIG. 2 is a block diagram illustrating a digital TV receiver accordingto some embodiments of the inventive concept;

FIG. 3A is a block diagram illustrating an example of a multi-stageequalizer/decoder in FIG. 2;

FIG. 3B is a block diagram illustrating another example of themulti-stage equalizer/decoder in FIG. 2;

FIG. 4 is a block diagram exemplarily illustrating a configuration of anequalizer/decoder unit which configures the multi-stageequalizer/decoder of FIG. 3A or the multi-stage equalizer/decoder ofFIG. 3B;

FIGS. 5A and 5B are timing diagrams showing an effect of someembodiments of the inventive concept; and

FIG. 6 is a graph schematically showing an effect of some embodiments ofthe inventive concept.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure now will be described more fully hereinafter withreference to the accompanying drawings, in which embodiments are shown.However, this disclosure should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the disclosure to those skilled in the art.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another element. Thus, a first element discussed belowcould be termed a second element without departing from the scope of thepresent invention. In addition, as used herein, the singular forms “a”,“an” and “the” are intended to include the plural forms as well, unlessthe context clearly indicates otherwise. It also will be understoodthat, as used herein, the term “comprising” or “comprises” isopen-ended, and includes one or more stated elements, steps and/orfunctions without precluding one or more unstated elements, steps and/orfunctions. The term “and/or” includes any and all combinations of one ormore of the associated listed items.

It will also be understood that when an element is referred to as being“connected” to another element, it can be directly connected to theother element or intervening elements may be present. In contrast, whenan element is referred to as being “directly connected” to anotherelement, there are no intervening elements present. It will also beunderstood that the sizes and relative orientations of the illustratedelements are not shown to scale, and in some instances they have beenexaggerated for purposes of explanation.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andthis specification and will not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. The present disclosurewill now be described more fully hereinafter with reference to theaccompanying drawings, in which preferred embodiments may be shown. Thisdisclosure, however, may be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the invention to thoseskilled in the art.

It should be construed that forgoing general illustrations and followingdetailed descriptions are exemplified and an additional explanation isprovided.

Reference numerals are indicated in detail in some embodiments of thepresent disclosure, and their examples are represented in referencedrawings. Throughout the drawings, like reference numerals are used forreferring to the same or similar elements in the description anddrawings.

Various embodiments of the present disclosure are described below withreference to block diagrams illustrating methods, apparatus and computerprogram products according to various embodiments of the disclosure. Itwill be understood that each block of the block diagrams and/oroperational illustrations, and combinations of blocks in the blockdiagrams and/or operational illustrations, can be implemented by analogand/or digital hardware, and/or computer program instructions. Thesecomputer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, ASIC, and/or otherprogrammable data processing apparatus, such that the instructions,which execute via the processor of the computer and/or otherprogrammable data processing apparatus, create means for implementingthe functions/acts specified in the block diagrams and/or operationalillustrations. Accordingly, it will be appreciated that the blockdiagrams and operational illustrations support apparatus, methods andcomputer program products.

Other software, such as an operating system, also may be included. Itwill be further appreciated that the functionality of the riskprediction module 100 and/or other modules described herein may beembodied, at least in part, using discrete hardware components, one ormore Application Specific Integrated Circuits (ASIC) and/or one or morespecial purpose digital processors and/or computers.

Below, a digital television (TV) broadcasting system using an ATSC 8-VSBscheme is used as one example for illustrating characteristics andfunctions of the present invention. However, those skilled in the artcan easily understand other advantages and performances of the presentinvention according to the descriptions herein. The present inventionmay be embodied or applied through other embodiments. Besides, thedetailed description may be amended or modified according to viewpointsand applications, not being out of the scope, technical idea and otherobjects of the present invention. Hereinafter, some embodiments of theinventive concept will be described in detail with reference to theaccompanying drawings.

FIG. 1 is a block diagram illustrating a structure of a Trellis-CodedModulation (TCM) encoder of a digital broadcasting system according tosome embodiments of the present invention.

Referring to FIG. 1, a TCM encoder used in an ATSC 8-VSB transmissionsystem includes a pre-coder 10, a trellis encoder 20, and a symbolmapper 30. Herein, transmission data {X₂, X₁} is 2-bit unit data where arandomizing operation, a Reed-Solomon (RS) encoding operation and aninterleaving operation have been completed on a transmission signal.

The pre-coder 10 encodes a bit X₂ corresponding to Most Significant Bit(MSB) in the transmission data {X₂, X₁}. An XOR logic operation isperformed on the bit X₂ (MSB) and a previous bit that is12-symbol-delayed by the pre-coder 10, and thus a bit Y₂ is outputted.Through such a scheme, the pre-coder 10 performs a pre-coding operationon the bit X₂ (MSB) to add correlation with respect to apreviously-encoded bit. The bit Y₂ processed by the pre-coder 10 istransferred as a bit Z₂ to the symbol mapper 30 without additionallyprocessing of the trellis encoder 20.

The trellis encoder 20 is a 4-state encoder that encodes one input bitinto two bits. The trellis encoder 20 processes a bit X₁ (=Y₁)corresponding to Least Significant Bit (LSB) among the transmission data{X₂, X₁} in a trellis encoding scheme based on an illustrated algorithmto output two bits {Z₁, Z₀}. Therefore, one input bit X₁ (=Y₁) isencoded into 2-bit data {Z₁, Z₀} by using a Viterbi code having a coderate of 1/2. A bit Z₁ is outputted as the same bit value as the bit X₁(=Y₁) that is not encoded. However, a bit Z₀ is generated as a bithaving correlation with a bit before 12 symbols and 24 symbols byViterbi encoding on the bit X₁ (=Y₁). 2-bit transmission data {X₂, X₁}is transferred as a 3-bit combination {Z₂, Z₁, Z₀} to the symbol mapper30 by the trellis encoder 20.

The symbol mapper 30 maps the 3-bit combination {Z₂, Z₁, Z₀} to an8-level VSB symbol (R). For example, a symbol level corresponding to{110} is mapped to +5, and a symbol level corresponding to {011} ismapped to −1.

In the above-described TCM encoder, an error correction ability that isprovided by the trellis encoder 20 in a single carrier scheme may not beparticularly strong. Therefore, high output energy may be used toimprove reception performance at a poor environment. However, in areceiver having a multi-stage equalizer-decoder structure according tosome embodiments of the inventive concept, the operated result of an RSdecoder may be used in a TCM decoder. That is, a priori information onthe transmission data {X₂, X₁} that is generated in the RS decoder maybe used for the soft-decision operation of the TCM decoder.

FIG. 2 is a block diagram illustrating a digital TV receiver accordingto some embodiments of the inventive concept.

Referring to FIG. 2, a digital TV receiver 100 includes a tuner 110, ademodulator 120, a multi-stage equalizer/decoder 130, a de-randomizer140, a de-interleaver 150, an RS decoder 160, and a TS packet generator170.

The tuner 110 down-converts a Radio Frequency (RF) signal, which may bereceived as a carrier frequency through an antenna, into a basebandsignal. When the RF signal is mixed with an oscillation frequencygenerated by a local oscillator (not shown), the RF signal of a carrierband may be down-converted into an Intermediate Frequency (IF) band.Herein, the received RF signal may be a VSB signal that is modulated ina single carrier modulation scheme or a multi-carrier modulation scheme.The tuner 110 may convert the received signal of a selected band into afixed IF signal and provide the converted signal to the demodulator 120.

The demodulator 120 converts the VSB signal, which is down-convertedinto the IF band by the tuner 110, into a bit stream. For example, thedemodulator 120 may include an analog-to-digital (A/D) converter (notshown) that converts the VSB signal into a digital signal. Thedemodulator 120 may output the VSB signal as a symbol sequence (or a bitstream).

The multi-stage equalizer/decoder 130 performs an adaptive channelequalization, TCM decoding and RS decoding on the symbol sequenceoutputted from the demodulator 120. A decision feedback equalizer isused for the adaptive channel equalization, a TCM decoder is used forthe TCM decoding, and an RS decoder is used for the RS decoding.Generally, the compensation effect of Inter-Symbol Interference (ISI) inthe decision feedback equalizer is largely affected by reliability ofthe decision value of the TCM decoder. Moreover, reliability of the TCMdecoder may increase according to the presence of a priori informationused for a soft-decision operation or the amount of the information.

In the multi-stage equalizer/decoder 130 according to some embodimentsof the inventive concept, a priori information of the transmission data{X₂, X₁} generated through the RS decoder may be provided to the TCMdecoder. Therefore, the TCM decoder may determine data at highreliability. Moreover, the TCM decoder feeds back a state metric (forexample, an optimal survivor path metric or a branch metric) or adecision value to the decision feedback equalizer. The decision feedbackequalizer may receive an equalizer initial value having high accuracy.Accordingly, the multi-stage equalizer/decoder 130 can output datahaving high reliability at a time variable and multipath channelenvironment.

To provide a more detailed description on the structure and/oroperations of the multi-stage equalizer/decoder 130, at least 2-stageequalizing and decoding (TCM and RS) operations are performed. In afirst equalizing and decoding stage, the multi-stage equalizer/decoder130 sequentially performs an adaptive channel equalizing operation, TCMdecoding and RS decoding on a received symbol. The multi-stageequalizer/decoder 130 interleaves and dibitizes RS-decoded data andconverts the data into a sequence corresponding to the transmission data{X₂, X₁}.

In a second equalizing and decoding stage, the multi-stageequalizer/decoder 130 performs an adaptive channel equalizing operation,TCM decoding and RS decoding on a symbol sequence through the sameoperation as that of the first equalizing and decoding stage.Particularly, after the second equalizing and decoding stage, a dibitgenerated through the decoding operation of a previous stage is used asa priori information for performing a TCM decoding operation. If thesecond equalizing and decoding stage is the last stage, the multi-stageequalizer/decoder 130 outputs a Transport Stream (TS) that is generatedafter second channel equalizing, de-interleaving and RS decoding on asymbol sequence.

The de-randomizer 140 performs a de-randomizing operation on a transportstream provided from the multi-stage equalizer/decoder 130. Thede-randomizer 140 performs a de-randomizing operation to a randomizingoperation performed in a transmitter, and thereby recovers a sequenceinto a symbol sequence upon transmission.

The de-interleaver 150 receives an output of the de-randomizer 140 andsequences the output in the reverse order of the interleaving scheme ofthe transmitter. When errors are scattered, a convolution code appliedto a Viterbi algorithm may have a relatively higher error correctionability. However, when errors intensively occur in a specific symbol ordata according to channel characteristic, it may not be easy to recoverdata. For example, if a burst error occurs, it may be difficult tocorrect the burst error because the errors are concentrated in aspecific data field.

Therefore, the transmitter (not shown) allows burst errors, which mayoccur in a channel through interleaving, to be scattered in a symbol ordata sequence. In the receiver, the TCM decoder (not shown) of themulti-stage equalizer/decoder 130 recovers an interleaved symbolsequence. The de-interleaver 150 re-sequences data interleaved by thetransmitter in reverse order. Even when the data re-sequenced by thede-interleaver 150 includes a burst error, it has a scattered errorpattern.

The RS decoder 160 corrects the error of data that is interleaved in anRS code scheme. Even an uncorrectable packet error may be detected by along RS decoder. An ATSC VSB transmission system uses an RS (207, 187,t=10) decoder. That is, the size of a data block is 187 bytes, andtwenty RS additional bytes are added for error correction. An entire RSblock having a 207-byte size is transmitted per data segment.

The TS packet generator 170 generates a TS MPEG stream with a decodedsymbol sequence.

As described above, the multi-stage equalizer/decoder 130 may repeat RSdecoding and apply a priori information, which is generated through theRS decoding, to TCM decoding. Through repetition of RS decoding, thecorrection probability of an uncorrectable error can increase.Reliability of TCM decoding can increase by providing of a prioriinformation. Furthermore, as accuracy of TCM decoding increases,compensation performance for ISI of an equalizer which receives a TCMdecoded result through feedback can considerably increase.

FIG. 3A is a block diagram illustrating an example of the multi-stageequalizer/decoder in FIG. 2.

Referring to FIG. 3A, the configuration of the multi-stageequalizer/decoder 130 having a 3-stage structure is exemplarilyillustrated.

The multi-stage equalizer/decoder 130 includes a first equalizer/decoder131, a second equalizer/decoder 133, and a third equalizer/decoder 135.The configurations or operation characteristics of the second and thirdequalizer/decoders 133 and 135 may be set identically. Alternatively,the configurations of the first to third equalizer/decoders 131, 133 and135 are the same, but the operations of the first to thirdequalizer/decoders 131, 133 and 135 may be set in order for only aspecialized function to be activated according to purposes.

First, demodulated data or a symbol sequence that is provided from thedemodulator 120 (see FIG. 2) is inputted to the data input terminalr_(t) of the first equalizer/decoder 131. The first equalizer/decoder131 performs an adaptive channel equalizing operation on the inputsymbol sequence. Furthermore, the first equalizer/decoder 131 performs adecoding operation on data that is generated through a channelequalizing operation, according to a TCM decoding operation. The decodeddata is re-sequenced in a time domain through a de-interleavingoperation.

Subsequently, the first equalizer/decoder 131 performs first RS decodingto generate a first transport stream. The first transport stream isre-sequenced through an interleaving operation that is again performed,thereby being converted into a dibit. The first equalizer/decoder 131transfers the dibit to an output terminal Lout. The firstequalizer/decoder 131 transfers a delayed symbol sequence to an outputterminal r_(t-d) without separate processing. However, the firsttransport stream may be transferred to a transport stream outputterminal TSout, but is not inputted to the second equalizer/decoder 133.

A symbol sequence provided from the first equalizer/decoder 131 isprovided to the second equalizer/decoder 133 through a data inputterminal r_(t). The second equalizer/decoder 133 processes the inputsymbol sequence according to the same operation as that of the firstequalizer/decoder 131. However, the second equalizer/decoder 133 uses adibit, which is provided from the first equalizer/decoder 131 through aninput terminal Lin, as a priori information for TCM decoding.

The TCM-decoded data is re-sequenced in a time domain through ade-interleaving operation. The second equalizer/decoder 133 performssecond RS decoding on de-interleaved data to generate a second transportstream. The second transport stream is re-sequenced through aninterleaving operation that is again performed, thereby being convertedinto a dibit. The second equalizer/decoder 133 transfers the dibit to anoutput terminal Lout. The second equalizer/decoder 133 transfers adelayed symbol sequence to an output terminal r_(t-d) without separateprocessing. However, the second transport stream may be transferred to atransport stream output terminal TSout, but is not inputted to the thirdequalizer/decoder 135.

The third equalizer/decoder 135 processes a symbol sequence inputtedfrom the second equalizer/decoder 133 on the basis of the dibit providedfrom the second equalizer/decoder 133. The third equalizer/decoder 135processes the symbol sequence according to the same operation as that ofthe second equalizer/decoder 133. That is, the third equalizer/decoder135 performs an adaptive channel equalizing operation on the inputsymbol sequence. Furthermore, the third equalizer/decoder 135 performsTCM decoding on data that is generated through the adaptive channelequalizing operation. The TCM-decoded data is re-sequenced in a timedomain through a de-interleaving operation. Subsequently, the thirdequalizer/decoder 135 performs third RS decoding on the datare-sequenced in the time domain to generate a third transport stream.The third equalizer/decoder 135 transfers the third transport stream toan output terminal TSout. Then, the third transport stream is outputtedas an output signal.

The above-described multi-stage equalizer/decoder 130 uses a dibit,which is generated through RS decoding for increasing accuracy of TCMdecoding, as a priori information. Therefore, in the multi-stageequalizer/decoder 130, accuracy of TCM decoding can considerablyincrease. Also, the filtering performance of an equalizer to which theresult of TCM decoding is fed back can be serially enhanced.

Herein, the multi-stage equalizer/decoder 130 configured in three stageshas been exemplified above for describing the technical feature of theinventive concept. However, some embodiments of the inventive conceptare not limited thereto. That is, the second equalizer/decoder 133 maybe omitted in the multi-stage equalizer/decoder 130, and the multi-stageequalizer/decoder 130 may be configured as a 2-stage equalizer/decoderwhere the first and third equalizer/decoders 131 and 135 are connectedin cascade. Alternatively, the multi-stage equalizer/decoder 130 mayinclude at least two or more equalizer/decoder units between the firstand third equalizer/decoders 131 and 135.

FIG. 3B is a block diagram illustrating another example of themulti-stage equalizer/decoder in FIG. 2.

Referring to FIG. 3B, the structure of a multi-stage equalizer/decoder130′ configured in N+1 stages is exemplarily illustrated.

The multi-stage equalizer/decoder 130′ includes N−1st-stageequalizer/decoders 133′ between a first-stage equalizer/decoder 131 anda last-stage equalizer/decoder 135. Like the multi-stageequalizer/decoder 130 of FIG. 3A, a symbol sequence provided from thedemodulator 120 (see FIG. 2) is inputted to the data input terminalr_(t) of the first-stage equalizer/decoder 131. The first-stageequalizer/decoder 131 performs an adaptive channel equalizing operationon the input symbol sequence. Furthermore, the first-stageequalizer/decoder 131 performs TCM decoding on data that is generatedthrough a channel equalizing operation. The TCM-decoded data isre-sequenced in a time domain through de-interleaving.

Subsequently, the first-stage equalizer/decoder 131 performs first RSdecoding to generate a first transport stream. The first transportstream is re-sequenced through interleaving that is again performed, andis converted into a dibit. The first-stage equalizer/decoder 131transfers the dibit to an output terminal Lout. The first-stageequalizer/decoder 131 transfers a delayed symbol sequence to an outputterminal r_(t-d) without separate processing. However, the firsttransport stream may be transferred to a transport stream outputterminal TSout, but may not be inputted to a second-stageequalizer/decoder.

The N−1st-stage equalizer/decoders 133′ repeat the above-describedprocessing operation of the second equalizer/decoder 133 N−1 times. Thedibit generated by the N-1st-stage equalizer/decoders 133′ and thesymbol sequence that is delayed without separate processing aretransferred to the last-stage equalizer/decoder 135.

The last-stage equalizer/decoder 135 processes the symbol sequenceinputted from the N−1st-stage equalizer/decoders 133′ on the basis ofthe dibit. The last-stage equalizer/decoder 135 performs an adaptivechannel equalizing operation on the input symbol sequence. Thelast-stage equalizer/decoder 135 performs TCM decoding on data that isgenerated through a channel equalizing operation. The TCM-decoded datais re-sequenced in a time domain through de-interleaving. Subsequently,the last-stage equalizer/decoder 135 performs last RS decoding on thedata re-sequenced in the time domain to generate a last transportstream. The last-stage equalizer/decoder 135 transfers the lasttransport stream to an output terminal TSout. Then, the last transportstream is provided as an output signal Dout.

The above-described multi-stage equalizer/decoder 130′ uses a dibit,which is generated through RS decoding for increasing accuracy of TCMdecoding, as a priori information. Therefore, in the multi-stageequalizer/decoder 130′, accuracy of TCM decoding can considerablyincrease. Equalizer/decoder units may be serially connected in amulti-stage structure, and thus a priori information generated throughRS decoding may be applied to TCM decoding.

FIG. 4 is a block diagram exemplarily illustrating a configuration of anequalizer/decoder unit which configures the multi-stageequalizer/decoder 130 of FIG. 3A or the multi-stage equalizer/decoder130′ of FIG. 3B. The first to third equalizers/decoders 131, 133 and 135of FIG. 3A may be configured identically to an equalizer/decoder unit200, respectively. Also, the first-stage to last-stageequalizers/decoders 131, 133′ and 135 of FIG. 3B may be configuredidentically to the equalizer/decoder unit 200, respectively.

Referring to FIG. 4, the equalizer/decoder unit 200 includes a PNsynchronizer 210, an equalizer 220, a TCM decoder 230, a de-interleaver240, an RS decoder 250, an interleaver 260, a dibit converter 270, aFirst-In, First-Out (FIFO) 280, and a delay 290.

When a symbol sequence r_(t) is inputted to the equalizer/decoder 200,the symbol sequence r_(t) is transferred through three paths. First, aPN sequence transmitted by the PN synchronizer 210 is synchronized. Thesymbol sequence r_(t) is inputted to the equalizer 220 and filtered. Thesymbol sequence r_(t) inputted to the delay 290 is synchronized with atransport stream and a dibit that are outputted from theequalizer/decoder unit 200.

The equalizer 220 may be configured as a decision feedback equalizerthat applies survivor path information, which is fed back from the TCMdecoder 230, to update of an equalizer coefficient. Particularly, afinal decision value that is decided by tracing a survivor path from theTCM decoder 230 may be used for updating the equalizer coefficient.However, when using all path metrics 233 to update the equalizercoefficient, a more enhanced performance of an equalizer can be secured.The equalizer 220 may use data 231, which is decided from the TCMdecoder 230, to update the equalizer coefficient.

The equalizer 220 may be configured with a feedforward part and afeedback part. Alternatively, the equalizer 220 may be configured as arecursive equalizer that divides a symbol sequence into a plurality ofsections and recursively performs a high-speed equalizer coefficientadaptation operation on each of the divided sections.

The TCM decoder 230 decodes an output signal (i.e., an equalized output)from the equalizer 130 according to a trellis code decoding algorithmhaving an error correction ability. The TCM decoder 230 may performdecoding on an input symbol to a corresponding decoding depth. When adecoding depth is large, decision can be made as an accurate data valuebecause a trace-back size increases.

The TCM decoder 230 receives a priori information that may increasereliability of a soft-decision operation. That is, except for anequalizer/decoder unit that performs an initial operation on a symbolsequence transferred, an equalizer/decoder unit corresponding to 2 ormore stages receives a dibit generated in a previous stage through aninput terminal Lin. The TCM decoder 230 may increase a branch metricwith the received dibit.

The de-interleaver 240 receives the output of the TCM decoder 230 andsequences the received output in the reverse order of the interleavingscheme of the transmitter. A convolution code applied to a Viterbialgorithm has a relatively higher error correction ability when errorsare scattered. However, when errors intensively occur in a specificsymbol or data according to channel characteristic, it may not be easyto recover data. For example, if a burst error occurs, it is difficultto correct the burst error because errors are concentrated in a specificdata field.

Therefore, the transmitter (not shown) allows burst errors, which occurin a channel through interleaving, to be scattered in a symbol or datasequence. In the receiver, the TCM decoder 230 recovers an interleavedsymbol sequence. The de-interleaver 240 re-sequences data which isinterleaved by the transmitter on the output of the TCM decoder 230, inreverse order. Even when the data re-sequenced by the de-interleaver 240includes a burst error, it has a scattered error pattern.

The RS decoder 250 corrects the error of data that is interleaved in anRS code scheme. Even an uncorrectable packet error may be detected by along RS decoder. An ATSC VSB transmission system uses an RS (207, 187,t=10) decoder. That is, the size of a data block is 187 bytes, andtwenty RS additional bytes are added for error correction. An entire RSblock having a 207-byte size is transmitted per data segment.

When using a multi-stage equalizer/decoder scheme, an RS decoder mayrecursively perform error correction on a transport stream. Although anerror may not be corrected in an initial stage, there is muchpossibility that an error may be corrected in RS decoding that isperformed after the initial stage.

The interleaver 260, the dibit converter 270 and the FIFO 280 areadditional elements for providing a transport stream, which iserror-corrected by the RS decoder 250, as a priori information to acontinuous multi-stage equalizer/decoder. The interleaver 260 processesthe output of the RS decoder 250 according to the same operation such asa scheme that is performed in the transmitter. The dibit converter 270converts the data of a byte unit into the dibit of a 2-bit unit. TheFIFO 280 stores and outputs dibits in a FIFO scheme.

In the above description, the exemplary configuration of theequalizer/decoder unit 200 configuring one stage has been described. Allequalizer/decoder units included in the multi-stage equalizer/decoder130 may be configured identically to the above-describedequalizer/decoder unit 200. However, a specific output may be used ordiscarded according to a position that is inserted into the multi-stageequalizer/decoder 130.

FIGS. 5A and 5B are timing diagrams showing an effect of someembodiments of the inventive concept. That is, the effects of themulti-stage equalizer/decoder are compared in FIGS. 5A and 5B, in a mainchannel, a ghost delay (1 μs) and a 2-channel condition having 1 dBattenuation characteristic compared to the main channel. FIG. 5A showstransmission errors in a typical receiver that does not use amulti-stage equalizer/decoder. FIG. 5B shows that the error of atransport stream which is not corrected by the decision feedbackequalizer can be efficiently removed.

FIG. 6 is a graph schematically showing an effect of an embodiment ofthe inventive concept. In FIG. 6, performance of the receiver accordingto an embodiment of the inventive concept applying the multi-stageequalizer/decoder and performance of the typical receiver are shown inthe main channel, the ghost delay (1 μs) and a 2-channel conditionhaving 1 dB attenuation characteristic compared to the main channel. Itis shown that the signal to noise ratio (SNR) of the receiver accordingto some embodiments of the inventive concept has improved by about 1 dBcompared to the typical receiver, in a picture fail point(TS−PER=0.0001).

In the digital TV receiver and data processing method thereof accordingto some embodiments of the inventive concept, digital broadcasting datahaving high reliability can be received even in the multipath and timevariable channel.

The above-disclosed subject matter is to be considered illustrative andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments, which fall withinthe true spirit and scope of the inventive concept. Thus, to the maximumextent allowed by law, the scope of the inventive concept is to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing detailed description.

1. A receiver for processing a vestigial sideband (VSB) signal, thereceiver comprising: a first equalizer/decoder unit that is configuredto perform a first equalizing operation, a first Trellis-CodedModulation (TCM) decoding and a first Reed-Solomon (RS) decoding on areceived symbol to output a first dibit; and a second equalizer/decoderunit that is configured to perform a second equalizing operation, asecond TCM decoding and a second RS decoding on the received symbol tooutput a transport stream, wherein the first dibit is provided as apriori information for a soft-decision operation of the second TCMdecoding.
 2. The receiver of claim 1, wherein a path metric or adecision value generated through the second TCM decoding is provided asfeedback information for the second equalizing operation.
 3. Thereceiver of claim 2, wherein an equalizer coefficient adaptationoperation is performed responsive to the feedback information in thesecond equalizing operation.
 4. The receiver of claim 1, wherein thefirst equalizer/decoder unit comprises: a first equalizer that isconfigured to perform the first equalizing operation; a first TCMdecoder that is configured to perform the first TCM decoding on anoutput of the first equalizer according to a Viterbi algorithm; a firstde-interleaver that is configured to de-interleave an output of thefirst TCM decoder; a first RS decoder that is configured to perform thefirst RS decoding on an output of the first de-interleaver; a firstinterleaver that is configured to interleave an output of the first RSdecoder; and a dibit converter that is configured to convert a byteoutput of the first interleaver into the dibit.
 5. The receiver of claim4, wherein the first equalizer comprises a decision feedback equalizerthat is configured to apply survivor path information from the TCMdecoder to update of an equalizer coefficient.
 6. The receiver of claim5, wherein the first TCM decoder provides a path metric or a decisionvalue based on the first TCM decoding to the first equalizer.
 7. Thereceiver of claim 4, wherein the first equalizer/decoder unit furthercomprises: a delay module that is configured to delay a transfer of thereceived symbol to the second equalizer/decoder unit; and a First-In,First-Out (FIFO) buffer that is used in the transfer of the dibit to thesecond equalizer/decoder unit.
 8. The receiver of claim 1, wherein thesecond equalizer/decoder unit comprises: a second equalizer that isconfigured to perform the second equalizing operation; a second TCMdecoder that is configured to perform the second TCM decoding on anoutput of the second equalizer by using the dibit as a prioriinformation; a second de-interleaver that is configured to de-interleavean output of the second TCM decoder; and a second RS decoder that isconfigured to perform the second RS decoding on an output of the secondde-interleaver to output the transport stream.
 9. The receiver of claim8, wherein: the second equalizer comprises a decision feedbackequalizer, and a path metric or a decision value based on the second TCMdecoding is fed back from the second TCM decoder to the secondequalizer.
 10. The receiver of claim 8, wherein the secondequalizer/decoder unit further comprises: a second delay module that isconfigured to delay and output the received symbol that is transferredfrom the first equalizer/decoder unit; a second interleaver that isconfigured to interleave the transport stream from the second RSdecoder; a second dibit converter that is configured to convert a byteoutput of the second interleaver into a second dibit; and a First-In,First-Out (FIFO) buffer that is configured to buffer the second dibit.11. The receiver of claim 1, further comprising a thirdequalizer/decoder unit disposed between the first and secondequalizer/decoder units, wherein the third equalizer/decoder unit isconfigured to sequentially perform a third equalizing operation on thereceived symbol, a third TCM decoding which uses the first dibit as apriori information and third RS decoding to generate a third dibit, andwherein the third dibit is provided to the second equalizer/decoderunit.
 12. The receiver of claim 1, further comprising a plurality ofequalizer/decoder units disposed between the first and secondequalizer/decoder units, wherein the plurality of equalizer/decoderunits are each configured to sequentially perform an equalizingoperation, a TCM decoding and an RS decoding on the received symbol,respectively.
 13. The receiver of claim 12, wherein each of theplurality of equalizer/decoder units provides a dibit generated throughthe RS decoding and the received symbol delayed to a nextequalizer/decoder unit.
 14. A method for processing a vestigial sideband(VSB) reception signal in a receiver including a decision feedbackequalizer, the method comprising: performing a first equalizingoperation, a first Trellis-Coded Modulation (TCM) decoding and a firstReed-Solomon (RS) decoding on a received symbol to output a first dibit;and performing a second equalizing operation, a second TCM decoding anda second RS decoding on the received symbol to output a transportstream, wherein the first dibit is provided as a priori information fora soft-decision operation of the second TCM decoding.
 15. The method ofclaim 14, further comprising performing an equalizer coefficientadaptation operation responsive to feedback information in the secondequalizing operation.
 16. The method of claim 14, wherein performing thefirst equalizer operation comprises applying survivor path informationfrom the TCM decoding to update an equalizer coefficient.
 17. The methodof claim 16, wherein the first TCM decoding provides a path metric or adecision value.
 18. The method of claim 4, further comprising delaying atransfer of the received symbol to the second equalizer/decoder unit;and buffering the dibit in a First-In, First-Out (FIFO) buffer beforeperforming the second equalizing operation.
 19. The method of claim 14,further comprising: performing the second TCM decoding on an outputcorresponding to the second equalizing operation by using the dibit as apriori information; de-interleaving an output corresponding to thesecond TCM decoding; and performing the second RS decoding on an outputcorresponding to the second de-interleaving and outputting the transportstream.
 20. The method of claim 14, further comprising delaying andoutputting the received symbol corresponding to performing the firstequalizing; and buffering a second dibit using a First-In, First-Out(FIFO) buffer. 21-25. (canceled)